Measuring Blood Pressure


Lt Col Reynolds
If you’ve ever seen a blood pressure reading, you know that there are two numbers, one over the other. And you know that if the numbers are too high, you have hypertension. But what do those numbers really mean? Let’s hear from Dr. Phillips to learn more about how blood pressure is measured.

Dr. Phillips
When someone measures your blood pressure, you’ll see two numbers listed. The top number reflects your systolic blood pressure, and the bottom number is your diastolic blood pressure. Your systolic blood pressure measures the force that your heart generates while the muscle is squeezing down, or contracting, to force blood into the circulatory system.

Your arteries, which are blood vessels that carry blood from your heart to the rest of your body, are flexible and elastic. Diastolic blood pressure represents the pressure in your arteries between heartbeats.

Blood pressure measurements are taken with an inflatable cuff that has a pressure gauge attached to it. The cuff goes around your upper arm. Your provider will use a stethoscope just below the cuff to listen to your pulse while watching the pressure gauge.

The cuff is inflated to the point that it briefly stops the blood-flow. The air is released slowly, and your provider listens with the stethoscope. When the pressure of the blood coming from the heart is equal to the pressure of the cuff, your provider will hear your pulse through the stethoscope and record the number on the pressure gauge, which gives a reading in millimeters of mercury (mmHg). This first measurement is your systolic blood pressure. It has a normal range of 90 to 120 mmHg.

When the last pulse is heard through the stethoscope, the blood is flowing smoothly through the artery. Your provider records the number shown on the pressure gauge at that moment. This is your diastolic blood pressure. It has a normal range of 60 to 80 millimeters of mercury.